Baltimore City police officials continued to investigate Monday after a 32-year-old unarmed Marine, Tyrone Brown, was fatally shot by an off-duty police officer, outside a nightclub early Saturday.

According to Baltimore City police, 36-year-old police officer Gahji Tshamba fired 13 rounds at Brown at close range, hitting him with six bullets. Brown, a 32-year old Marine who has served two tours of duty in Iraq, died shortly thereafter.

Witnesses told police the violence erupted after Brown made advances toward a woman who was with the officer.

Baltimore police spokesman Anthony Guglielmi said Tshamba, a 15-year veteran, shot a man in the foot after a confrontation while off duty in 2005. Tshamba was disciplined at the time because it was discovered he was under the influence of alcohol.

Police said they are investigating whether alcohol was a factor in this incident as Officer Tshamba declined to take a breathalyzer test. .

Brown’s sister, La-Belle Scott told WBAL-TV in Baltimore that she was there when her brother was shot.

“There was absolutely no physical contact,” she said. “The supposed officer was not in any harm whatsoever. He (Brown) had his hands up to show he didn’t have no weapons or anything.”